A method of making a three-dimensional object by laminating sintered layers is known in, for example, Japanese Laid-Open Patent Publication No. 1-502890, wherein an optical beam (directional energy beam, for example, a laser) is first irradiated on a powdery layer formed on a table to form a sintered layer. The sintered layer thus obtained is then covered with a new powdery layer, on which the optical beam is irradiated to form a new sintered layer. These processes are repeatedly carried out to form a three-dimensional object in which a plurality of sintered layers are laminated one above another.
This prior art includes a powder supply unit for supplying a powdery material onto the table, which is accommodated in a chamber held in a predetermined atmosphere, to form a powdery layer, and also includes an optical beam-irradiating unit disposed outside the chamber for irradiating an optical beam on the powdery layer through a light transmitting window (including a window made up of a lens) disposed immediately above the table.
When the powdery material is irradiated with a high energy optical beam for sintering (in some cases, the powdery material is solidified after once melted), fumes (for example, metallic vapor when metallic powder is employed as the powdery material) are generated. The fumes rise and adhere or stick to the window disposed immediately above them, thereby clouding up the window and lowering the permeability to the optical beam. Accordingly, it becomes impossible to stabilize the sintering or increase the density of sintered portions, resulting in a reduction in strength of a three-dimensional object. The permeability to the optical beam is also reduced by the scattering and floating powder or the powder that has been caused to adhere to the window.
In addition, the three-dimensional object obtained upon completion of the sintering is taken out from the chamber, but Japanese Laid-Open Patent Publication No. 1-502890 discloses no removing mechanism, and the three-dimensional object is manually taken out under the existing circumstances.
However, the object to be made has a size of, for example, 500 mm×500 mm×100 mm, and if it is made from a metallic powdery material having a specific gravity of, for example, 6-8, the object obtained comes to have a weight of 150-200 kg. Because manual removal of the object of such a weight is most unlikely, a crane is employed. In an apparatus having an optical beam-irradiating unit above a table, however, the optical beam-irradiating unit must be moved at the time of removal of the object by the crane. In this case, the repeatability for positioning of an optical axis is lost and, hence, the machining accuracy lowers considerably or adjusting work is needed whenever the shaping is conducted.
In an apparatus as disclosed in Japanese Laid-Open Patent Publication No. 2002-527613, because the side of the table is movable, interference between the optical beam-irradiating unit and the crane can be avoided. In this case, however, there is a good chance that the powder may be gotten caught in the movable table and incline it and, hence, it becomes difficult to ensure the repeatability for positioning of the optical axis, and a very complicated mechanism is needed.
The present invention has been developed to overcome the above-described disadvantages.
It is accordingly a primary objective of the present invention to provide a method of and apparatus for making a three-dimensional object that is not affected by fumes or scattering powder.
Another objective of the present invention is to provide a method of and apparatus for making a three-dimensional object that can facilitate removal of a shaped object from a chamber.